Use of macrocyclic metal complexes as temperature sensors

ABSTRACT

PCT No. PCT/EP94/01376 Sec. 371 Date Mar. 8, 1996 Sec. 102(e) Date Mar. 8, 1996 PCT Filed Apr. 29, 1994 PCT Pub. No. WO94/27977 PCT Pub. Date Dec. 8, 1994The invention relates to the use of macrocyclic metal complexes that consist of a complexing agent of formula I and at least one metal ion of an element of atomic numbers 21-29, 42, 44 or 57-70    set forth in the specification, are useful as temperature sensors.

This application is a 371 of PCT/EP94/01376 filed Apr. 29, 1994,published as WO94/27977 Dec. 8, 1994.

The invention relates to the object characterized in the claims, i.e.,the use of macrocyclic metal complexes as temperature sensors in NMRnuclear magnetic resonance! diagnosis.

With the aid of modern diagnostic methods, it is possible to depictextremely small morphological structures at a resolution that comesclose to that of the tissue sections of anatomy textbooks. Thisenormously high resolution is achieved, on the one hand, by constantlyimproved hardware, but, on the other hand, also with the aid of contrastmedia. With the various known methods, such as ultrasonic diagnosis,diagnostic radiology, nuclear medicine and even nuclear spin tomography,however, it is not possible to obtain information on themetabolic-physiological state of a tissue in the living organism. For amore exact diagnosis and especially for planning and monitoring thecourse of therapeutic intervention, however, such knowledge is ofconsiderable importance, since an optimum treatment can be successfulonly if a statement on its effect is possible early on.

It is known that an important factor in metabolic-physiological activityis temperature. The determination of this tissue temperature providesimportant information on the function and state of the cells, so that itis desirable to locate sites that have temperatures which deviate fromnormal body temperature. This makes it possible to identifypathologically altered tissue and optionally to perform treatment.

Body temperature is a product of the activity of energy metabolism andis subject to varied influences.

Blood flow represents a significant value of influence on local tissuetemperature; via blood flow the body attempts to offset temperaturedrops that occur constantly K. Bruck, Heat Balance and TemperatureRegulation, in: Physiologie des Menschen Human Physiology!, R. F.Schmidt, G. Thews (Editors), Springer Verlag, 23rd Edition, 1987!. Themeasurement of temperature therefore offers a way to delimit localincreased blood circulation (e.g., in the case of inflammations) orrestricted blood circulation (e.g., in ischemic regions) in a tissueagainst its healthy environs.

In the case of hyperthermia treatment for tumor diseases, themeasurement of tissue temperature is an important parameter formonitoring the course of the radiation. At the moment, only invasivemethods can be used for this purpose P. Fessenden, Direct TemperatureMeasurement, in: Hyperthermia in Cancer Treatment, Cancer Research, 44(Suppl.), 4703s-4709s, 1984!.

It is now known that the chemical shift of signals in in vitro NMRspectroscopy is also a function of temperature. This influence is causedby intermolecular and intramolecular interactions. In high-resolutionNMR spectroscopy, intermolecular interactions, e.g., with the solvent,quite decisively determine the chemical shift. The solvation of themolecule under study, including intermolecular aggregation and hydrogenbridging, depends greatly on temperature. Hydrogen bridge bonds arebroken at elevated temperatures and thus change the chemical environmentof the atomic nuclei. In the case of substances that form strongintermolecular hydrogen bridge bonds, the temperature coefficient of thechemical shift is especially large. With the aid of calibration curves,temperature can then be determined exactly from the chemical shift thatis measured empirically. In this case, particularly the aliphaticalcohols, which tend toward strong hydrogen bridge bonds, have proven tobe of value:

Methanol CH₃ OH: T=409.0-36.54Δδ-21.85(Δδ)²

Ethylene glycol HOCH₂ --CH₂ OH: T=466.5-102.00Δδ in which Δδ is thedifference in the chemical shifts between the OH and CH signals in ppmand T is absolute temperature in K R. Duerst, A. Merbach, Rev. Sci.Instrum. 36, 1896 (1965)!.

The change in the chemical shift with temperature due to intermolecularinteraction is by no means limited to the proton; rather it is a generalproperty of all magnetically active atomic nuclei, so that a wholeseries of temperature standards have been proposed in the literature.

    ______________________________________                                                                Temp.-gradient                                        Standard Substance                                                                        Atomic Nuclei                                                                             ppm/K      Literature*                                ______________________________________                                        Methanol    proton      0.015      (1)                                        ethylene glycol                                                                           proton      0.016      (1),(9)                                    CH.sub.2 I.sub.2 /cyclooctane                                                             carbon      0.07       (2)                                        CH.sub.3 I/tetramethyl-                                                                   carbon      0.02       (2)                                        silane                                                                        MgATP complex                                                                             phosphorus  0.012      (3),(9)                                    K.sub.3 Co(CN).sub.6                                                                      cobalt      1.504      (4),(9)                                    Co-acetylacetonate                                                                        cobalt      3.153      (4),(9)                                    (CBrF.sub.2).sub.2 /CClF2).sub.2                                                          fluorine    0.0071     (5)                                        CFCl.sub.3 /CBr.sub.2 F.sub.2                                                             fluorine    0.0012     (5)                                        perfluorotributyl-                                                                        fluorine    0.0003     (6)                                        amine                                                                         (CH.sub.3).sub.2 TlNO.sub.3                                                               thallium    0.44       (7)                                        methanol    deuterium   0.015      (8)                                        ______________________________________                                         *See bibliographic index                                                 

Further, a ¹³ C--NMR thermometer has been proposed which is based on thechange in the complexing constants between shifting reagent Yb(fod)₃ andacetone H. J. Schneider, W. Freitag, M. Schommer, J. Magn. Reson. 18,393 (1973)!. This process can be used only in organic solvents, however.

In virtually all organic compounds, the influence of intramolecularinteractions on the chemical shift is too small to be able to use it fortemperature measurements. In the literature, only one example of thistype is described, in which the intramolecular rotational barrier infurfural and the associated linear changes in the ¹³ C--NMR spectrumwere used for temperature measurement S. Combrisson, T. Prange, J. Magn.Reson. 19, 108 (1973)!. This process is suitable, however, only in avery narrow temperature range, and this measurement range dependsgreatly on the magnetic measuring field strength used.

Use of these methods for in vivo temperature measurement of body tissuesis as yet unsuccessful, however, for various reasons. For instance, mostof the compounds described in the literature cannot be mixed with water,or are soluble only in nonpolar organic solvents, such as chloroform.Thus, use in intact biological systems is virtually impossible. Althoughthe introduction of a pure perfluorotributylamine bubble into a rabbit'seye and subsequent temperature measurement are possible B. A. Berkowitz,J. T. Handa, C. A. Wilson, NMR in Biomedicine 5, 65 (1992)!, thisprocess is highly invasive and cannot be transferred to other organs.Some of the water-soluble compounds such as methanol, ethylene glycol,K₃ Co(CN)₆ and thallium salts must be excluded from the start because oftheir high toxicity. Of the substances described, theoretically only theMgATP complex is suitable as an endogenous temperature sensor. Since therelative MgATP concentration in cytosol is small (around 10 mmol/kg) andcannot be increased by external administration because of thecreatinine-kinase equilibrium and since in addition the phosphorusnuclei are insensitive and the chemical shift is also heavily dependenton the ionic strength and the pH of the medium, a precise temperaturedetermination with ³¹ P--NMR measurements of MgATP within a reasonabletime is not possible. Thus, all temperature sensors that are describedin the literature are unsuitable for an in vivo temperature measurementin routine clinical diagnosis.

The object of this invention was therefore to find suitable compoundsfor in vivo temperature measurement by means of NMR spectroscopy.

These compounds must meet the following requirements:

a) They must react to a change of temperature with a changed resonancefrequency in the NMR spectrum,

b) They must exhibit a pronounced chemical shift per degree oftemperature change,

c) They must exhibit pharmacokinetics that is suitable for diagnosticapplications,

d) They must exhibit a concentration in the target tissues that is highenough for measuring,

e) They must exhibit good compatibility and low toxicity,

f) They must exhibit metabolic stability,

g) They must exhibit high chemical stability and long shelf life and

h) They must exhibit good water-solubility.

It has now been found that macrocyclic metal complexes that consist ofat least one metal ion of an element of atomic numbers 21-29, 42, 44 or57-70 and a complexing agent of general formula I ##STR2## in which nmeans the numbers 0 or 1,

R¹ independently of one another, stand for a hydrogen atom or a metalion equivalent,

R³ stands for a hydrogen atom, a straight-chain or branched C₁ -C₁₀alkyl group, which is optionally substituted by 1-5 C₁ -C₆ alkoxygroups, hydroxy-C₁ -C₆ alkyl groups and/or hydroxy groups,

R² means a straight-chain or branched C₁ -C₁₀ alkylene group, whichoptionally is interrupted by 1 to 5 oxygen atoms and/or carbonyl groupsand/or optionally is substituted by 1 to 5 hydroxy groups, C₁ -C₆alkoxy-C₁ -C₆ alkyl groups, --OR⁴, --CO--NR⁵ R⁶, --NR⁵ R⁶ and/or --NR⁵--CO--R⁶ radicals,

in which R⁴ stands for a straight-chain or branched C₁ -C₄ alkyl radicaland R⁵, R⁶, independently of one another, have the meaning of R³, and

A stands for a hydrogen atom or a second macrocyclic radical of generalformula II, ##STR3## in which n, R¹ and R³ have the indicated meanings,where free carboxylic acid groups that are not required for complexingthe metal ions are present optionally as a salt of an inorganic ororganic base or amino acid and/or as an ester or amide and at least tworadicals R¹ stand for a metal ion equivalent, are suitable astemperature sensors in NMR diagnosis.

Preferred are compounds in which R³ stands for a hydrogen atom and R²--A stands for a --CH₂ CH₂ OCH₃, --CH₂ CH₂ O--C(CH₃)₃, --CH₂--CH(OH)--CH₂ OCH₃, --CH₂ CH(OH)--CH₂ O--CH(CH₃)₂, --CH₂ --CH(OH)--CH₂O--C(CH₃)₃, --CH₂ --CH(OH)--CH₃, --CH(CH₂ OCH₃)₂, --CH(CH₂OCH₃)--CH(OH)CH₂ OH, --CH₂ --CH₂ --NH--CH₃, --CH₂ --CH₂ --N(CH₃)₂, --CH₂--CO--N(CH₃)₂, --CH₂ --CH₂ --O--CH₂ --CH₂ --O--CH₃, or --C(CH₂ OCH₃)₃group.

Especially preferred from this group are radicals R² --A, such as, e.g.,--CH₂ CH₂ OCH₃ --, --CH₂ CH₂ O--C(CH₃)₃, since the latter exhibit asmaller line width and therefore the change of the chemical shift can bedetermined more precisely.

Surprisingly enough, the changes in the chemical shifts of theabove-mentioned complex compounds in the case of small concentrations,as are used for in vivo applications, are essentially intramolecular inorigin and thus are independent of outside influences, such as ionicstrength, pH, and oxygen partial pressure, i.e., the dependence of thechemical shift on temperature is based only on the interaction between acentral ion and the atomic nuclei present in the ligand.

It is further surprising that this chemical shift, which is caused byintramolecular interaction, can be used for in vivo temperaturemeasurement.

The temperature gradients depend on the measured atomic nuclei, thechemical structure of the ligand, and the central ion.

As central atoms, paramagnetic metal ions, especially those of thelanthanoid elements, are especially suitable.

It has been found, surprisingly enough, that the temperature effect onthe chemical shift of the signals caused by the complexes does not movein the same direction for all complexes. Thus, e.g., the methoxy groupsignal of the europium complex (produced according to Example 6h) isshifted toward a low field and that of the corresponding praseodymiumcomplex (produced according to Example 6c) is shifted toward a higherfield, i.e, the praseodymium complex exhibits a positive temperaturegradient, while the europium complex shows a negative temperaturegradient. Thus, the possibility arises of considerably increasing theprecision of the temperature measurement by mixing the two complexes inthe diagnostic tools.

FIG. 1 shows a superposition of the in vitro spectra of theabove-mentioned europium and praseodymium complexes in D₂ O that arerecorded at room temperature. The singlet at -23 ppm corresponds to themethoxy group of the praseodymium complex, and the singlet at 11.2 ppmcorresponds to the methoxy group of the europium complex. The signal ofD₂ O was used as an internal standard. To determine the temperaturegradients, a 0.01 molar solution of the complexes in question in D₂ Owas produced. Of the respective solutions, spectra at varioustemperatures in the range between 46° C. and 26° C. were recorded. Fromthese measurements, a temperature gradient of 0.145 ppm/K follows forthe praseodymium complex (produced according to Example 6c).

FIG. 2 shows the time change of the NMR spectrum during the cooling ofthe solution of the above-mentioned praseodymium complex. Taking intoconsideration the line width, a measuring accuracy of 0.3° C. results.

These data for five of the compounds shown in the Examples is shown inthe following table.

    ______________________________________                                                                Tem-              Relative                                                    perature          Accuracy                            Sub-                    Gra-        Chem- of Mea-                             stance                                                                              Cen-   Signal-    dient Line  ical  surement                            Exam- tral   Transmitting                                                                             (ppm/ Width Shift (ppm/                               ple No.                                                                             Atom   Group      K)    (Hz)  (ppm) Hz · K)                    ______________________________________                                        1d    Sm     CH.sub.2 CH(OH)-                                                                         0.012 8     -1.36 1.5 × 10.sup.-3               CH.sub.2 OCH.sub.3                                                            2b    Sm     CH.sub.2 CH(OH)-                                                                         0.011 8.5   -3.50 1.3 × 10.sup.-3               CH.sub.2 O.sup.t Bu                                                           2c    Eu     CH.sub.2 CH(OH)-                                                                         0.010 8     -2.5  1.25 ×                        CH.sub.2 O.sup.t Bu           10.sup.-3                                       6c    Pr     CH.sub.2 CH.sub.2 OCH.sub.3                                                              0.145 25    -21   5.8 × 10.sup.-3               6h    Eu     CH.sub.2 CH.sub.2 OCH.sub.3                                                              -0.055                                                                              15    12    3.7 × 10.sup.-3               ______________________________________                                    

A quite critical advantage of this family of compounds for localized invivo ¹ H-NMR spectroscopy lies in the fact that the signals used fortemperature measurement appear outside the spectral range of allendogenous substances, including tissue water. This allows the almostdistortion-free measurement of temperature-sensitive signals thanks togreatly simplified suppression of intense background signals for NMRspectroscopy.

The great flexibility of the chemical structure of the ligand, which canbe adapted to the measuring problem to be solved, offers anotheradvantage. By appropriately adjusting, e.g., longitudinal relaxationtime T¹ of the measurement signal, optimum sensitivity can be achieved.For localized spectroscopic methods, which are based on a spin echo,transversal relaxation time T₂ can be adjusted optimally in the sameway.

The production of the complexing agents of general formula I (i.e., ofcompounds in which R¹ stands for a hydrogen atom) is done as describedin European Patents EP 0 299 795, EP 0 434 345, EP 0 434 346 and EP 0255 371.

Compounds of formula I, in which R³ does not equate to hydrogen, can beproduced as described in DE 41 40 779, by side chain --R² --A beingfirst introduced by reacting the corresponding epoxide withtricyclotridecane. After cleavage of the formyl group of theintermediate product produced, the product thus obtained is reacted witha compound of general formula III, ##STR4## in which X stands for anucleofuge, e.g., for a halogen or a sulfonyloxy radical and R⁷ standsfor a hydrogen atom or for an acid protective group, preferably for atert-butyl group.

Instead of the tricyclotridecane used above, tris(benzyloxycarbonyl)cyclene can also be alkylated with epoxides (see J. Chem. Soc. PerkinTrans. I, 12, 3329 1991!).

The epoxides that are required for reactions can be produced accordingto the processes known to one skilled in the art.

The reaction of 1,4,7-triscarboxymethyl-1,4,7,10-tetraazacyclododecanewith epoxides is done in solvents at temperatures of between 10° and150° C., preferably at 50°-80° C. As solvents, all inert polar solventsare suitable. The reaction is done with the addition of bases. The basescan be added in solid or dissolved form. The bases that can beconsidered include lithium hydroxide, sodium hydroxide, potassiumhydroxide, alkali- and alkaline-earth carbonates, and -oxides, ororganic bases, such as tertiary amines, e.g., triethylamine ordiisopropylethylamine, N-methyl-morpholine or tetramethylpiperidine.

The reaction of 1,4,7-triscarboxymethyl-1,4,7,10-tetraazacyclododecanewith halogen compounds can also be done in solid or liquid form.Preferred solvents are dioxane, tetrahydrofuran, dimethylformamide,dimethylacetamide and methanol, ethanol, propanol, isopropanol andwater. The reaction is done with the addition of bases (as indicatedabove) at temperatures of between 40° C. and 150° C., preferably at 75°to 110° C.

The production of the metal complexes according to the invention fromthese complexing agents is done in the way that was disclosed in Germanlaid-open specification DE 34 01 052, as well as in European PatentApplications EP 0 450 742 and EP 0 413 405, by dissolving or suspendingthe metal oxide or a metal salt (for example, nitrate, acetate,carbonate, chloride or sulfate) of the element of atomic numbers 21-29,42, 44, 57-70 in water and/or a lower alcohol (such as methanol, ethanolor isopropanol) and reacting the equivalent amount of complexing ligandwith the solution or suspension, and then, if desired, substitutingpresent acid hydrogen atoms by cations of inorganic and/or organic basesor amino acids.

The neutralization of free acid groups that are optionally still presentis done with the aid of inorganic bases (for example, hydroxides,carbonates or bicarbonates) of, for example, sodium, potassium, lithium,magnesium or calcium and/or organic bases, such as, i.a., primary,secondary and tertiary amines, such as, for example, ethanolamine,morpholine, glucamine, N-methylglucamine and N,N-dimethylglucamine, aswell as basic amino acids, such as, for example, lysine, arginine andornithine or amides of initially neutral and acidic amino acids.

For the production of neutral complex compounds, for example, enough ofthe desired bases can be added to the acid complex salts in aqueoussolution or suspension to ensure that the neutral point is reached. Thesolution obtained can then be evaporated to dryness in a vacuum. Often,it is advantageous to precipitate the neutral salts that are formed byadding water-miscible solvents, such as, for example, lower alcohols(methanol, ethanol, isopropanol and others), lower ketones (acetone andothers), or polar ethers (tetrahydrofuran, dioxane, 1,2-dimethoxyethaneand others) and thus to obtain crystallizates that are easily isolatedand readily purified. It has proven especially advantageous to add thedesired base as early as during complexing of the reaction mixture andas a result to eliminate a process step.

If the acid complex compounds contain several free acid groups, it isoften advisable to produce neutral mixed salts that contain bothinorganic and organic cations as counterions.

The pharmaceutical agents according to the invention are preferablyproduced in a concentration of 1 μmol-1 mol/l. They are generally dosedin amounts of 0.005-20 mmol/kg of body weight, preferably 0.05-5 mmol/kgof body weight. They are intended for enteral and parenteraladministration. The agents according to the invention meet the variedrequirements for suitability as diagnostic tools for NMR spectroscopy.Further, they possess the high effectiveness that is necessary to burdenthe body with the smallest possible amounts of foreign substances andthe good compatibility that is necessary to preserve the noninvasivenature of the studies.

The good water solubility and low osmolality of the agents according tothe invention make it possible to produce highly concentrated solutions,so that the volume burden on the circulatory system is kept withinreasonable limits and the dilution is compensated for by the bodilyfluid. Further, the agents according to the invention exhibit not onlyhigh stability in vitro, but also surprisingly high stability in vivo sothat any release or exchange of the ions that are bound in the complexesoccurs only extremely slowly within the time that it takes for the newcontrast media to be completely excreted again.

By using these very well-tolerated complexes as new measuring sensors,it has thus been possible to perform site-resolved spectroscopy in smallvolumes (e.g., 10 cm³) and to determine temperature precisely in shortermeasurement times without disruption or superposition by othermolecules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a superposition of the in vitro spectra of europium andpraseodymium complexes in D₂ O.

FIG. 2 shows the time change of the NMR spectrum during cooling of apraseodymium complex solution.

EXAMPLES

The following examples are used to explain the object of the invention,without intending that they be limited to this object.

EXAMPLE 1

a)10-(2-Hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

7.63 g (86.58 mmol) of glycidyl methyl ether and 10 g (28.86 mmol) of1,4,7-triscarboxymethyl-1,4,7,10-tetraazacyclododecane are dissolved ina mixture of 50 ml of dioxane/80 ml of water, and the pH is brought to10 with 6 N potassium hydroxide solution. It is stirred for 24 hours at50° C. It is evaporated to dryness, the residue is taken up with 300 mlof water/50 ml of methanol and extracted twice with 100 ml of tert-butylmethyl ether. The aqueous solution is adjusted to pH 1 with 5 Nhydrochloric acid and evaporated to dryness. The residue is boiled out(extracted) with 200 ml of methanol/80 ml of methylene chloride. It iscooled in an ice bath and precipitated potassium chloride is filteredout. The filtrate is concentrated by evaporation in a vacuum, theresidue is dissolved in 45 ml of water/20 ml of ethanol and then put ona column of poly-(4-vinylpyridine). The product is eluted with asolution of ethanol/water 1:3. After concentration by evaporation in avacuum, the residue is chromatographed on a reversed-phase column (RP18/mobile solvent =gradient of water/tetrahydrofuran). Afterconcentration by evaporation of the main fraction, 10.38 g (77% oftheory) of a greatly hygroscopic, vitreous solid is obtained.

Water content: 7.0%

Analysis (relative to anhydrous substance):

Cld: C 49.76 H 7.89 N 12.89

Fnd: C 49.54 H 7.98 N 12.70

b) Lanthanum complex of10-(2-hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododeca

5 g (11.51 mmol) of the title compound of Example 1a is dissolved in 50ml of water and 1.87 g (5.75 mmol) of lanthanum oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with2 ml of acidic ion exchanger (AMB 252c H⁺) and 2 ml of weakly basicexchanger IRA 67 (OH⁻ form) at room temperature. Exchanger is filteredout, and the filtrate is freeze-dried.

Yield: 6.56 g (95% of theory) of a vitreous solid

Water content: 4.9%

Analysis (relative to anhydrous substance):

Cld: C 37.90 H 5.48 N 9.82 La 24.35

Fnd: C 37.79 H 5.58 N 9.71 La 24.22

c) Praseodymium complex of10-(2-hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

5 g (11.51 mmol) of the title compound of Example 1a is dissolved in 50ml of water and 3.66 g (11.51 mmol) of praseodymium(III) acetate isadded. It is heated for 2 hours to 90° C. and then evaporated to drynessin a vacuum. The residue is taken up in 50 ml of water and againevaporated to dryness. The residue is dissolved in 100 ml of water andstirred for 1 hour with 2 ml of acidic ion exchanger (AMB 252c/H⁺ form)and 5 ml of weakly basic exchanger (IRA 67/OH⁻ form). Exchanger isfiltered out, and the filtrate is freeze-dried.

Yield: 6.75 g (96% of theory) of a light green solid

Water content: 6.3%

Analysis (relative to anhydrous substance):

Cld: C 37.77 H 5.46 N 9.79 Pr 24.62

Fnd: C 37.56 H 5.69 N 9.61 Pr 24.48

d) Samarium complex of10-(2-hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 1b, samarium oxide instead of lanthanum oxide wasused.

Yield: 95% of theory of a colorless solid

Water content: 6.9%

Analysis (relative to anhydrous substance):

Cld: C 37.16 H 5.37 N 9.63 Sm 25.84

Fnd: C 36.95 H 5.45 N 9.49 Sm 25.67

e) Europium complex of10-(2-hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 1b, europium oxide instead of lanthanum oxide wasused.

Yield: 93% of theory of an amorphous powder

Water content: 9.4%

Analysis (relative to anhydrous substance):

Cld: C 37.06 H 5.36 N 9.60 Eu 26.05

Fnd: C 36.84 H 5.51 N 9.47 Eu 25.87

f) Holmium complex of10-(2-hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 1b, holmium oxide instead of lanthanum oxide wasused.

Yield: 97% of theory of a pale pink fluorescent solid

Water content: 7.2%

Analysis (relative to anhydrous substance):

Cld: C 36.25 H 5.24 N 9.39 Ho 27.65

Fnd: C 36.13 H 5.31 N 9.28 Ho 27.48

g) Dysprosium complex of10-(2-hydroxy-3-methoxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 1b, dysprosium oxide instead of lanthanum oxidewas used.

Yield: 95% of theory of a colorless amorphous powder

Water content: 8.1%

Analysis (relative to anhydrous substance):

Cld: C 36.40 H 5.26 N 9.43 Dy 27.36

Fnd: C 36.28 H 5.37 N 9.31 Dy 27.28

EXAMPLE 2

a)10-(2-Hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

11.27 g (86.58 mmol) of glycidyl-tert-butyl ether and 10 g (28.86 mmol)of 1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane are dissolvedin a mixture of 50 ml of dioxane/80 ml of water, and the pH is broughtto 10 with 6 N potassium hydroxide solution. It is stirred for 24 hoursat 70° C. It is evaporated to dryness, the residue is taken up with 300ml of water/50 ml of methanol and extracted twice with 100 ml oftert-butyl-methyl ether. The aqueous solution is adjusted to pH 1 with 5N hydrochloric acid and evaporated to dryness. The residue is boiled out(extracted) with 200 ml of methanol/80 ml of methylene chloride. It iscooled in an ice bath and precipitated potassium chloride is filteredout. The filtrate is concentrated by evaporation in a vacuum, theresidue is dissolved in 45 ml of water/20 ml of ethanol and then put ona column of poly-(4-vinylpyridine). The product is eluted with asolution of ethanol/water 1:3. After concentration by evaporation in avacuum, the residue is chromatographed on a reversed-phase column (RP18/mobile solvent =gradient of water/tetrahydrofuran). Afterconcentration by evaporation of the main fraction, 10.38 g (71% oftheory) of a strongly hygroscopic, vitreous solid is obtained.

Water content: 5.9%

Analysis (relative to anhydrous substance):

Cld: C 52.93 H 8.46 N 11.76

Fnd: C 52.80 H 8.51 N 11.58

b) Samarium complex of10-(2-hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

5 g (10.49 mmol) of the title compound of Example 2a is dissolved in 50ml of water and 1.83 g (5.24 mmol) of samarium oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with2 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 2 ml of weakly basicexchanger IRA 67/OH⁻ form) at room temperature.

Yield: 6.77 g (96% of theory) of a vitreous solid

Water content: 7.2%

Analysis (relative to anhydrous substance):

Cld: C 40.43 H 5.98 N 8.98 Sm 24.10

Fnd: C 40.21 H 6.10 N 8.87 Sm 24.00

c) Praseodymium complex of10-(2-hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 1c, the title compound of Example 2a instead ofthe title compound of Example 1a was used for complexing.

Yield: 93% of theory of a greenish amorphous powder

Water content: 5.9%

Analysis (relative to anhydrous substance):

Cld: C 41.05 H 6.07 N 9.12 Pr 22.93

Fnd: C 40.90 H 6.20 N 9.01 Pr 22.74

d) Dysprosium complex of10-(2-hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 2b, dysprosium oxide instead of samarium oxidewas used.

Yield: 95% of theory of a colorless amorphous powder

Water content: 7.4%

Analysis (relative to anhydrous substance):

Cld: 39.66 H 5.86 N 8.81 Dy 25.55

Fnd: 39.49 H 5.98 N 8.70 Dy 25.38

e) Europium complex of10-(2-hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 2b, europium oxide instead of samarium oxide wasused.

Yield: 97% of theory of a colorless solid

Water content: 8.7%

Analysis (relative to anhydrous substance):

Cld: C 40.32 H 5.92 N 8.96 Eu 24.29

Fnd: C 49.18 H 5.99 N 8.71 Eu 24.05

f) Lanthanum complex of10-(2-hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 2b, lanthanum oxide instead of samarium oxide wasused.

Yield: 94% of theory of a colorless amorphous powder

Water content: 8.1%

Analysis (relative to anhydrous substance):

Cld: C 41.18 H 6.09 N 9.15 La 22.68

Fnd: C 41.04 H 6.17 N 9.02 La 22.49

g) Holmium complex of10-(2-hydroxy-3-tert-butyloxy-propyl)-1,4,7-tris-carboxymethyl-1,4,7,10-tetraazacyclododecane

Analogously to Example 2b, holmium oxide instead of samarium oxide wasused.

Yield: 97% of theory of a light red fluorescent powder

Water content: 5.9%

Analysis (relative to anhydrous substance):

Cld: C 39.51 H 5.84 N 8.78 Ho 25.83

Fnd: C 39.37 H 5.98 N 8.60 Ho 25.67

EXAMPLE 3

a) Lanthanum complex of10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

5 g (12.36 mmol) of10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecaneis dissolved in 50 ml of water and 2.01 g (6.18 mmol) of lanthanum oxideis added. It is stirred for 3 hours at 90° C. The solution is stirredfor one hour with 2 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 2ml of weakly basic exchanger (IRA 67/OH⁻ form) at room temperature.Exchanger is filtered out, and the filtrate is freeze-dried.

Yield: 6.53 g (94% of theory) of a vitreous solid

Water content: 3.8%

Analysis (relative to anhydrous substance):

Cld: C 37.79 H 5.41 N 10.37 La 25.71

Fnd: C 37.58 H 5.60 N 10.18 La 25.52

b) Samarium complex of10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 3a, title compound 3b was produced from samariumoxide and10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane.

Yield: 95% of theory of a colorless solid

Water content: 6.1%

Analysis (relative to anhydrous substance):

Cld: C 37.00 H 5.30 N 10.15 Sm 27.25

Fnd: C 36.88 H 5.41 N 10.02 Sm 27.10

c) Holmium complex of10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 3a, title compound 7c was produced from holmiumoxide and 10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane.

Yield: 97% of theory of a pale rose-colored solid

Water content: 8.7%

Analysis (relative to anhydrous substance):

Cld: C 36.05 H 5.16 N 9.89 Ho 29.12

Fnd: C 35.87 H 5.29 N 9.71 Ho 29.01

d) Europium complex of10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 3a, title compound 3d was produced from europiumoxide and10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane.

Yield: 97% of theory of colorless solid

Water content: 5.7%

Analysis (relative to anhydrous substance):

Cld: C 36.90 H 5.28 N 10.12 Eu 27.46

Fnd: C 36.71 H 5.41 N 9.97 Eu 27.31

e) Praseodymium complex of10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 1c,10-(2-hydroxy-propyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecaneinstead of the title compound of Example 1a was used for complexing.

Yield: 98% of theory of greenish solid

Water content: 5.9%

Analysis (relative to anhydrous substance):

Cld: C 37.65 H 5.39 N 10.33 Pr 25.98

Fnd: C 37.48 H 5.48 N 10.18 Pr 25.81

EXAMPLE 4

a)10-(6-Hydroxy-2,2-dimethyl-1,3-dioxepan-5-yl)-1,4,7-tris(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecane

40 g (126.4 mmol) of 10-(6-hydroxy-2,2-dimethyl-1,3-dioxepan-5-yl)-1,4,7,10-tetraazacyclododecane is dissolved in 400 mlof methylene chloride and 42.21 g (417.1 mmol) of triethylamine isadded. At 0° C., 71.16 g (417.1 mmol) of benzyl chloroformate isinstilled within one hour and stirred for one hour at 0° C., thenovernight at room temperature. It is mixed with 500 ml of water andstirred for 30 minutes. The organic phase is separated, dried onmagnesium sulfate and concentrated by evaporation in a vacuum. Theresidue is chromatographed on silica gel (mobile solvent =methylenechloride/acetone 20:1).

Yield: 79.05 g (87% of theory) of a colorless oil

Analysis:

Cld: C 65.16 H 7.01 N 7.79

Fnd: C 65.08 H 7.15 N 7.66

b)10-(1-(2,2-Dimethyl-1,3-dioxolan-4-yl)-2-hydroxyethyl)-1,4,7-tris(benzyloxy-carbonyl)-1,4,7,10-tetraazacyclododecane

7.8 g (108.5 mmol) of the title compound of Example 4a and 19.61 g(113.9 mmol) of p-toluenesulfonic acid are dissolved in 800 ml ofethanol and stirred for 3 hours at 70° C. It is evaporated to dryness,the residue is taken up with 500 ml of toluene and again evaporated todryness. This residue is taken up with 600 ml of toluene and 53.4 ml(434 mmol) of 2,2-dimethoxypropane is added. Then, it is stirred for 2hours at 80° C. The solution is cooled to room temperature and shakenout 3 times with 400 ml of 3 N sodium hydroxide solution. The organicphase is dried on magnesium sulfate and evaporated to dryness in avacuum. The residue is chromatographed on silica gel (Mobile solvent=methylene chloride/acetone 15:1).

Yield: 56.94 g (73% of theory) of a colorless oil

Analysis:

Cld: C 65.16 H 7.01 N 7.79

Fnd: C 64.95 H 6.88 N 7.68

c) 10-1-(2,2-Dimethyl-1,3-dioxolan-4-yl)-2-methoxyethyl!-1,4,7-tris(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecane

21.46 g (382.5 mmol) of potassium hydroxide (finely powdered) as well as500 mg of tetrabutylammonium hydrogen sulfate are added to 55 g (76.5mmol) of the title compound of Example 4b in 400 ml of methylenechloride. Within one hour, 12.61 g (100 mmol) of dimethyl sulfate isinstilled with vigorous stirring at room temperature. It is stirred for12 hours at room temperature. 400 ml of ice water is added and stirredfor 15 minutes. The organic phase is separated, dried on magnesiumsulfate and concentrated by evaporation in a vacuum. The residue ischromatographed on silica gel (mobile solvent =methylenechloride/acetone 20:1).

Yield: 52.14 g (93% of theory) of a colorless oil

Analysis:

Cld: C 65.56 H 7.15 N 7.64

Fnd: C 65.38 H 7.24 N 7.55

d) 1-1-(2,2-Dimethyl-1,3-dioxolan-4-yl)-2-methoxyethyl!-1,4,7,10-tetraazacyclododecane

51 g (69.6 mmol) of the title compound of Example 4c is dissolved in 600ml of ethanol and 5 g of palladium catalyst (10% Pd/C) is added. It ishydrogenated overnight at room temperature. The catalyst is filteredout, and the filtrate is evaporated to dryness in a vacuum.

Yield: 23 g (quantitative) of vitreous solid

Analysis:

Cld: C 58.15 H 10.37 N 16.95

Fnd: C 58.02 H 10.45 N 16.87

e) 10-(1-Methoxymethyl-2,3-dihydroxypropyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

8.35 g (25.28 mmol) of the title compound of Example 4d is dissolved in50 ml of water and 14.05 g (101.12 mmol) of bromoacetic acid is added.The pH is brought to 9.5 with 6 N potassium hydroxide solution. It isheated to 60° C. and the pH is kept between 9.5-10 by adding 6 Npotassium hydroxide solution. After 24 hours of stirring at 60° C., itis cooled in an ice bath, adjusted to pH 1 with concentratedhydrochloric acid and evaporated to dryness in a vacuum. The residue isdissolved in a little water and put on a cation-exchange column (IR120). After flushing with water, the ligand is eluted with 0.5 Nammonia-water solution. The fractions are concentrated by evaporation,the ammonium salt is taken up with a little water and put on ananion-exchange column (IRA 67). It is washed first with water and theneluted with 0.5 N aqueous formic acid. It is concentrated by evaporationin a vacuum, the residue is dissolved in a little hot methanol andacetone is added. After cooling in an ice bath, the title compoundcrystallizes out.

Yield: 6.94 g (53% of theory) of an amorphous, hygroscopic powder

Water content: 10.3%

Analysis (relative to anhydrous substance):

Cld: C 49.13 H 7.81 N 12.06

Fnd: C 49.02 H 7.95 N 11.87

f) Lanthanum complex of10-(1-methoxymethyl-2,3-dihydroxypropyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

5 g (10.76 mmol) of the title compound of Example 4e is dissolved in 50ml of water and 1.75 g (5.38 mmol) of lanthanum oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with2 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 2 ml of weakly basicexchanger (IRA 67/OH⁻ form) at room temperature. Exchanger is filteredout, and the filtrate is freeze-dried.

Yield: 6.76 g (97% of theory) of a vitreous solid

Water content: 6.1%

Analysis (relative to anhydrous substance):

Cld: 38.01 H 5.54 N 9.33 La 23.14

Fnd: 37.83 H 5.67 N 9.18 La 23.02

g) Dysprosium complex10-(1-methoxymethyl-2,3-dihydroxypropyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 4f, dysprosium oxide instead of lanthanum oxidewas used.

Yield: 93% of theory of a vitreous solid

Water content: 8.1%

Analysis (relative to anhydrous substance):

Cld: C 36.57 H 5.33 N 8.98 Dy 26.04

Fnd: C 36.41 H 5.41 N 8.77 Dy 25.84

h) Praseodymium complex of10-(1-methoxymethyl-2,3-dihydroxypropyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 1c, the title compound of Example 4e instead ofthe title compound of Example 1a was used for complexing.

Yield: 95% of theory of a greenish-colored solid

Water content: 8.3%

Analysis (relative to anhydrous substance):

Cld: C 37.88 H 5.52 N 9.30 Pr 23.39

Fnd: C 37.69 H 5.63 N 9.13 Pr 23.20

i) Europium complex of10-(l-methoxymethyl-2,3-dihydroxypropyl-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 4f, europium oxide instead of lanthanum oxide wasused.

Yield: 98% of theory of a colorless amorphous powder

Water content: 7.4%

Analysis (relative to anhydrous substance):

Cld: C 37.20 H 5.42 N 9.13 Eu 24.77

Fnd: C 37.01 H 5.61 N 9.04 Eu 24.58

EXAMPLE 5

a) 1,3-Dimethoxy-propyl-2-trifluoromethanesulfonate

46.96 g (166 mmol) of trifluoromethanesulfonic anhydride is instilled in20 g (166 mmol) of 1,3-dimethoxy-2-hydroxypropane and 16.8 g (166 mmol)of triethylamine in 400 ml of diethyl ether at -20° C. and stirred for 2hours at this temperature. Then, it is stirred for 2 hours at 0° C. Itis poured in 300 ml of 20% aqueous common salt solution and stirredvigorously. The organic phase is separated and extracted twice with 200ml of 20% aqueous common salt solution. The organic phase is dried onmagnesium sulfate and concentrated by evaporation in a vacuum.

Yield: 39.77 g (95% of theory) of a colorless oil (˜ 97% contentaccording to gradient chromatography) (It is further reacted withoutpurification in Example 5b)

Analysis:

Cld: C 28.57 H 4.40 F 26.60 S 12.69

Fnd: C 28.81 H 4.65 F 26.30 S 12.38

b) 10-1,1-Di(methoxymethyl)-methyl!-1,4,7-tris-(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecane

39 g (154.6 mmol) of the title compound of Example 5a and 44.43 g (77.3mmol) of 1,4,7-tris-(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecane(produced according to Chem. Soc., Perkin Trans. 1, 12:3329, 1991) and85.14 g (616 mmol) of potassium carbonate in 800 ml acetonitrile arerefluxed for 24 hours. Solid is filtered out, and the filtrate isevaporated to dryness in a vacuum. The residue is taken up in 700 ml ofmethylene chloride and extracted twice with 300 ml of water. The organicphase is dried on magnesium sulfate and concentrated by evaporation in avacuum. The residue is chromatographed on silica gel (mobile solvent=methylene chloride/methanol 20:1).

Yield: 18.31 g (35% of theory relative to amine) of a colorless oil

Analysis:

Cld: C 65.66 H 7.15 N 8.28

Fnd: C 65.47 H 7.28 N 8.13

c) 1- 1,1-Di(methoxymethyl)-methyl!-1,4,7,10-tetraazacyclododecane

18 g (26.6 mmol) of the title compound of Example 5b is dissolved in 300ml of ethanol and 4 g of palladium catalyst (10% Pd/C) is added. It ishydrogenated for 12 hours at room temperature. The catalyst is filteredout, and the filtrate is evaporated to dryness in a vacuum.

Yield: 7.3 g (quantitative) of a yellowish, viscous oil

Analysis:

Cld: C 56.90 H 11.02 N 20.42

Fnd: C 56.71 H 11.10 N 20.28

d) 10-1-Di(methoxymethyl)-methyl!-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

6.94 g (25.28 mmol) of the title compound of Example 5c is dissolved in50 ml of water and 14.05 g (101.12 mmol) of bromoacetic acid is added.The pH is brought to 9.5 with 6 N potassium hydroxide solution. It isheated to 60° C. and the pH is kept between 9.5-10 by adding 6 Npotassium hydroxide solution. After 24 hours of stirring at 60° C., itis cooled in an ice bath, adjusted to pH 1 with concentratedhydrochloric acid and evaporated to dryness in a vacuum. The residue isdissolved in a little water and put on a cation-exchange column (IR120). After flushing with water, the ligand is eluted with 0.5 Nammonia-water solution. The fractions are concentrated by evaporation,the ammonium salt is taken up with a little water and put on ananion-exchange column (IRA 67). It is washed first with water and theneluted with 0.5 N aqueous formic acid. It is concentrated by evaporationin a vacuum, the residue is dissolved in a little hot ethanol andacetone is added. After cooling in an ice bath, the title compoundcrystallizes out.

Yield: 7.71 g (61% of theory) of a hygroscopic solid

Water content: 10.3%

Analysis (relative to anhydrous substance):

Cld: C 50.88 H 8.09 N 12.49

Fnd: C 50.64 H 8.20 N 12.27

e) Lanthanum complex of 10-1-di(methoxymethyl)-methyl!-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

5 g (11.15 mmol) of the title compound of Example 5d is dissolved in 50ml of water and 1.82 g (5.57 mmol) of lanthanum oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with2 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 2 ml of weakly basicexchanger (IRA 67/OH⁻ form) at room temperature. Exchanger is filteredout, and the filtrate is freeze-dried.

Yield: 6.73 g (96% of theory) of a vitreous solid

Water content: 6.7%

Analysis (relative to anhydrous substance):

Cld: C 39.05 H 5.69 N 9.59 La 23.77

Fnd: C 38.84 H 5.78 N 9.41 La 23.60

f) Dysprosium complex of 10-1-di(methoxymethyl)-methyl!-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 5e, dysprosium oxide instead of lanthanum oxidewas used.

Yield: 93% of theory of a colorless solid

Water content: 7.3%

Analysis (relative to anhydrous substance):

Cld: C 37.54 H 5.47 N 9.21 Dy 26.73

Fnd: C 37.71 H 5.55 N 9.05 Dy 26.54

g) Europium complex of 10-1-di(methoxymethyl)-methyl!-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 5e, europium oxide instead of lanthanum oxide wasused.

Yield: 95% of theory of a colorless amorphous powder

Water content: 8.5%

Analysis (relative to anhydrous substance):

Cld: C 38.20 H 5.57 N 9.38 Eu 25.43

Fnd: C 38.03 H 5.68 N 9.24 Eu 25.28

h) Praseodymium complex of 10-1-di(methoxymethyl)-methyl!-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 1c, the title compound of Example 5d instead oftitle compound 1a was used for complexing.

Yield: 96% of theory of a green solid

Water content: 3.9%

Analysis (relative to anhydrous substance):

Cld: C 38.92 H 5.67 N 9.55 Pr 24.03

Fnd: C 38.73 H 5.75 N 9.47 Pr 23.84

EXAMPLE 6

a)10-(3-Oxa-butyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

3 g (8.66 mmol) of1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane is stirred in50 ml of dimethylformamide for 10 hours with 1.57 g (11.29 mmol) of2-methoxyethyl bromide and 4.15 g of potassium carbonate at 90° C. It isconcentrated by evaporation in a vacuum and the residue is spreadbetween 100 ml of water and 50 ml of diethyl ether. The aqueous phase isadjusted to pH 2 with 5 N hydrochloric acid and evaporated to dryness.The residue is refluxed with 200 ml of methanol, the undissolvedmaterial is filtered out, it is evaporated to dryness in a vacuum, theresidue is dissolved in 50 ml of water, adjusted to pH 2 with 5 Nhydrochloric acid and the solution is put on a column with 200 ml ofcation exchanger IRC 50. It is eluted first with 0.5 l of water, whichis discarded. Then, it is eluted with 0.5 l of 0.5 N ammonia solution.It is evaporated almost to dryness in a vacuum, mixed with 100 ml ofwater and enough cation exchanger IRC 50 is added with stirring until pH3.5 is reached. The solution is then filtered and freeze-dried. 2.49 gof the title compound with a water content of 4.30% is obtained.

Analysis (relative to anhydrous substance):

Cld: C 50.48 H 7.79 N 13.85

Fnd: C 50.31 H 7.91 N 13.95

b) Dysprosium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

2 g (4.95 mmol) of anhydrous substance of the title compound of Example6a is stirred in 25 ml of water with 922 mg of dysprosium oxide for 8hours at 85° C. It is cooled to room temperature and the solution isstirred for 1 hour with 1 ml of acidic ion exchanger (AMB 252c, H⁺ form)and 1 ml of basic ion exchanger (IRA 67, OH⁻ form). It is filtered,freeze-dried and 2.54 g of the title compound is obtained.

Water content: 5.1%

Analysis (relative to anhydrous substance):

Cld: C 36.20 H 5.18 Dy 28.81 N 9.93

Fnd: C 36.77 H 5.32 Dy 28.66 N 10.05

c) Praseodymium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

2.5 g (6.18 mmol, anhydrous substance) of the title compound of Example6a is stirred in 30 ml of water with 1.019 g (3.09 mmol) of praseodymiumoxide for 5 hours at 85° C. It is cooled to room temperature and thesolution is stirred for 1 hour with 1.3 ml of acidic ion exchanger (AMB252c, H⁺ form) and 1.3 ml of basic ion exchanger (IRA 67, OH⁻ form). Itis filtered, freeze-dried and 3.10 g of the title compound is obtainedwith a water content of 4.05% as light green solid.

Analysis (relative to anhydrous substance):

Cld: C 37.64 H 5.39 N 10.33 Pr 25.98

Fnd: C 37.96 H 5.49 N 10.32 Pr 25.69

d) Holmium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 6c, holmium(III) oxide instead of praseodymiumoxide is used.

Yield: 90% of theory of a colorless solid

Water content: 4.90%

Analysis (relative to anhydrous substance):

Cld: C 36.05 H 5.16 Ho 29.12 N 9.89

Fnd: C 36.35 H 5.41 Ho 29.01 N 9.97

e) Ytterbium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 6c, ytterbium(III) oxide instead of praseodymiumoxide is used.

Yield: 90% of theory of a colorless solid

Water content: 5.3%

Analysis (relative to anhydrous substance):

Cld: C 35.54 H 5.09 N 9.75 Yb 30.12

Fnd: C 35.80 H 5.31 N 9.80 Yb 30.07

f) Samarium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 6c, samarium(III) oxide instead of praseodymiumoxide is used.

Yield: 93% of theory of a colorless solid

Water content: 5.00%

Analysis (relative to anhydrous substance):

Cld: C 37.00 H 5.30 N 10.15 Sm 27.24

Fnd: C 37.32 H 5.52 N 10.09 Sm 27.02

g) Gadolinium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 6c, gadolinium oxide instead of praseodymiumoxide is used.

Yield: 91% of theory of a colorless solid

Water content: 5.05%

Analysis (relative to anhydrous substance):

Cld: C 36.54 H 5.23 Gd 28.14 N 10.02

Fnd: C 37.02 H 5.27 Gd 27.88 N 10.17

h) Europium complex of10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 6c, europium(III) oxide instead of praseodymiumoxide is used.

Yield: 95% of theory of a colorless solid

Water content: 4.30%

Analysis (relative to anhydrous substance):

Cld: C 36.89 H 5.28 Eu 27.46 N 10.12

Fnd: C 37.31 H 5.40 Eu 27.00 N 10.22

EXAMPLE 7

a)10-(4,4-Dimethyl-3-oxa-pentyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

5 g (14.43 mmol) of 1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane is stirred in 75 ml of dimethylformamide for 18hours with 3.14 g (17.35 mmol) of (2-bromoethyl)-tert-butyl ether and6.50 g of potassium carbonate at 95° C. It is concentrated byevaporation in a vacuum and the residue is dissolved in 100 ml of water,the pH is adjusted to 2 by adding 12 N hydrochloric acid and thesolution is put on a column of 320 ml of cation exchanger IR-120 (H⁺form). It is eluted with 2 l of water, which is discarded, then with 2 lof 0.5 N ammonia solution. This solution is concentrated by evaporationin a vacuum, the residue is dissolved in 100 ml of water. With stirring,enough cation exchanger IR-120 is added in portions up to pH 3.5. Thesolution is filtered and freeze-dried and 4.19 g of the title compoundis obtained as white solid with a water content of 6.3%.

Analysis (relative to anhydrous substance):

Cld: C 53.79 H 8.58 N 12.54

Fnd: C 54.01 H 8.49 N 12.70

b) Dysprosium complex of10-(4,4-dimethyl-3-oxa-pentyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

2.5 g (5.60 mmol, anhydrous substance) of the title compound of Example7a is stirred with 1.044 g of dysprosium oxide (2.80 mmol) in 30 ml ofwater for 5 hours at 90° C. After cooling, the solution is stirred for 1hour with 1.2 ml of acidic ion exchanger (AMB 252 c, H⁺ form) and 1.2 mlof basic ion exchanger (IRA 67, OH⁻ form). It is filtered, freeze-driedand 2.55 g of the title compound is obtained as solid.

Water content: 4.35%

Analysis (relative to anhydrous substance):

Cld: C 39.63 H 5.82 Dy 26.81 N 9.24

Fnd: C 39.83 H 5.90 Dy 26.60 N 9.32

c) Praseodymium complex of10-(4,4-dimethyl-3-oxa-pentyl)-1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 7b, praseodymium(III) oxide instead of dysprosiumoxide is used.

Yield: 72% of a light green solid

Water content: 4.2%

Analysis (relative to anhydrous substance):

Cld: C 41.10 H 6.04 N 9.59 Pr 24.11

Fnd: C 41.29 H 6.30 N 9.68 Pr 23.95

EXAMPLE 8

a) 1,4-Di4,7,10-tris(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,3-dihydroxybutane

44.43 g (77.3 mmol) of1,4,7-tris-(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecane (producedaccording to Chem. Soc. Perkin Trans 1, 12: 3329, 1991) and 2.21 g(25.67 mmol) of 1, 2-3,4-diepoxybutane in 200 ml of n-butanol arerefluxed for 3 days. It is evaporated to dryness in a vacuum and theresidue is chromatographed on silica gel (mobile solvent: methylenechloride/hexane/acetone =20/10/1).

Yield: 15.22 g (48% of theory relative to 1,2-3,4-diepoxybutane) of aviscous oil

Analysis:

Cld: C 66.11 H 6.69 N 9.07

Fnd: C 66.03 H 6.80 N 9.15

b) 1,4-Di4,7,10-tris(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,3-dimethoxybutane

8.52 g (60 mmol) of methyl iodide is added to 15 g (12.14 mmol) of thetitle compound of Example 8a and 1.44 g (60 mmol) of sodium hydride in200 ml of dimethylformamide and stirred for 48 hours at 60° C. 1000 mlof water is added and extracted twice with 300 ml of ethyl acetate. Thecombined organic phases are extracted twice with 500 ml of water, thenthe organic phase is dried on magnesium sulfate and evaporated todryness in a vacuum. The residue is purified on silica gel (mobilesolvent: methylene chloride/hexane/acetone =20/10/1).

Yield: 13.65 g (89% of theory) of a colorless oil

Analysis:

Cld: C 66.54 H 6.86 N 8.87

Fnd: C 66.39 H 6.95 N 8.71

c) 1,4-Di 1,4,7,10-tetraazacyclododecan-1-yl!-2,3-dimethoxybutane

13.5 g (10.68 mmol) of the title compound of Example 8b is dissolved in300 ml of ethanol and 4 g of palladium catalyst (10% Pd/C) is added. Itis hydrogenated for 12 hours at room temperature. The catalyst isfiltered out, and the filtrate is evaporated to dryness in a vacuum.

Yield: 4.9 g (quantitative) of a slightly cream-colored solid

Analysis:

Cld: C 57.61 H 10.99 N 24.43

Fnd: C 57.51 H 10.93 N 24.48

d) 1,4-Di4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,3-dimethoxybutane

4.8 g (10.46 mmol) of the title compound of Example 8c is dissolved in80 ml of water and 13.96 g (100.5 mmol) of bromoacetic acid is added.The pH is brought to 9.5 with 6 N potassium hydroxide solution. It isheated to 60° C. and a pH between 9.5-10 is obtained by adding 6 Npotassium hydroxide solution. After 24 hours of stirring at 60° C., itis cooled in an ice bath, adjusted to pH 1 with concentratedhydrochloric acid and evaporated to dryness in a vacuum. The residue isdissolved in a little water and put on a cation-exchange column (IR120). After flushing with water, the ligand is eluted with 0.5 Nammonia-water solution. The fractions are concentrated by evaporation,the ammonium salt is taken up with a little water and put on ananion-exchange column (IRA 67). It is washed first with water and theneluted with 0.5 N aqueous formic acid. It is concentrated by evaporationin a vacuum, the residue is dissolved in a little hot ethanol andacetone is added. After cooling in an ice bath, the title compoundcrystallizes out.

Yield: 4.77 g (51% of theory) of a hygroscopic solid

Water content: 9.7%

Analysis (relative to anhydrous substance):

Cld: C 50.61 H 7.74 N 13.89

Fnd: C 50.50 H 7.81 N 13.78

e) Bis-praseodymium complex of 1,4-di4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,3-dimethoxybutane

4.5 g (5.577 mmol) of the title compound of Example 8d is dissolved in50 ml of water and 1.84 g (5.577 mmol) of praseodymium oxide is added.It is stirred for 3 hours at 90° C. The solution is stirred for one hourwith 2 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 2 ml of weaklybasic exchanger (IRA 67/OH⁻ form) at room temperature. Exchanger isfiltered out, and the filtrate is freeze-dried.

Yield: 6.47 g (97% of theory) of a vitreous solid

Water content: 6.3%

Analysis (relative to anhydrous substance):

Cld: C 37.72 H 5.21 N 10.35 Pr 26.03

Fnd: C 37.65 H 5.29 N 10.24 Pr 25.95

EXAMPLE 9

a) 1,7-Di4,7,10-tris(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,6-dihydroxy-4-oxaheptane

44.43 g (77.3 mmol) of1,4,7-tris-(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecane (producedaccording to Chem. Soc. Perkin Trans 1, 12: 3329, 1991) and 3.34 g(25.67 mmol) of 1, 2-6,7-diepoxy-4-oxa-heptane in 200 ml of n-butanolare refluxed for 3 days. It is evaporated to dryness in a vacuum and theresidue is chromatographed on silica gel (mobile solvent: methylenechloride/hexane/acetone =20/10/1).

Yield: 17.74 g (54% of theory relative to 1,2-6,7-diepoxy-4-oxa-heptane) of a viscous oil.

Analysis:

Cld: C 65.71 H 6.77 N 8.76

Fnd: C 65.65 H 6.84 N 8.70

b) 1,7-Di4,7,10-tris(benzyloxycarbonyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,6-dimethoxy-4-oxaheptane

9.65 g (68 mmol) of methyl iodide is added to 17.5 g (13.68 mmol) of thetitle compound of Example 9a and 1.64 g (68 mmol) of sodium hydride in230 ml of dimethylformamide and it is stirred for 48 hours at 60° C.1000 ml of water is added and extracted twice with 300 ml of ethylacetate. The combined organic phases are extracted twice with 500 ml ofwater, then the organic phase is dried on magnesium sulfate andevaporated to dryness in a vacuum. The residue is purified on silica gel(mobile solvent: methylene chloride/hexane/acetone =20/10/1).

Yield: 15.74 g (88% of theory) of a colorless oil

Analysis:

Cld: C 66.14 H 6.94 N 8.57

Fnd: C 64.07 H 6.91 N 8.61

c) 1,7-Di(1,4,7,10-tetraazacyclododecan-1-yl)-2,6-dimethoxy-4-oxaheptane

15.5 g (11.85 mmol) of the title compound of Example 9b is dissolved in300 ml of ethanol and 4 g of palladium catalyst (10% Pd/C) is added. Itis hydrogenated for 12 hours at room temperature. The catalyst isfiltered out, and the filtrate is evaporated to dryness in a vacuum.

Yield: 5.96 g (quantitative) of a slightly cream-colored solid

Analysis:

Cld: C 57.34 H 10.83 N 22.29

Fnd: C 57.28 H 10.90 N 22.19

d) 1,7-Di4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,6-dimethoxy-4-oxaheptane

5.8 g (11.54 mmol) of the title compound of Example 9c is dissolved in100 ml of water and 16.03 g (115.4 mmol) of bromoacetic acid is added.The pH is brought to 9.5 with 6 N potassium hydroxide solution. It isheated to 60° C. and the pH is kept between 9.5-10 by adding 6 Npotassium hydroxide solution. After 24 hours of stirring at 60° C., itis cooled in an ice bath, adjusted to pH 1 with concentratedhydrochloric acid and evaporated to dryness in a vacuum. The residue isdissolved in a little water and put on a cation-exchange column (IR120). After flushing with water, the ligand is eluted with 0.5 Nammonia-water solution. The fractions are concentrated by evaporation,the ammonium salt is taken up with a little water and put on ananion-exchange column (IRA 67). It is washed first with water and theneluted with 0.5 N aqueous formic acid. It is concentrated by evaporationin a vacuum, the residue is dissolved in a little hot ethanol andacetone is added. After cooling in an ice bath, the title compoundcrystallizes out.

Yield: 6.65 (61% of theory) of a hygroscopic solid

Water content: 10.1%

Analysis (relative to anhydrous substance):

Cld: C 50.81 H 7.82 N 13.17

Fnd: C 50.74 H 7.85 N 13.05

e) Bis europium complex of 1,7-di4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl!-2,6-dimethoxy-4-oxaheptane

6.5 g (7.638 mmol) of the title compound of Example 9d is dissolved in50 ml of water and 2.68 g (7.638 mmol) of europium oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with2 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 2 ml of weakly basicexchanger (IRA 67/OH-form) at room temperature. Exchanger is filteredout, and the filtrate is freeze-dried.

Yield: 9.26 g (98% of theory) of a vitreous solid.

Water content: 7.2%

Analysis (relative to anhydrous substance):

Cld: C 37.64 H 5.26 N 9.75 Eu 26.45

Fnd: C 37.53 H 5.30 N 9.70 Eu 26.35

EXAMPLE 10

For selected complexes, in vitro measurements that were suitable fordetermining various parameters significant for temperature measurementwere made. To this end, a 0.01 molar aqueous solution was produced fromthe respective complex and measured at various temperatures in the rangebetween 46° C. and 26° C. The intense signal of the solvent (H₂ O) wassuppressed by selective pre-saturation and by the use of narrow-bandaudio filters. The results of these studies are summarized in FIG. 3/3.

EXAMPLE 11

a)4-(α,α,α-Tris(hydroxymethyl)-methyl)-1,7-bis(p-tolylsulfonyl)-1,4,7-triazaheptane

143.3 g (726 mmol) of tosylaziridine is added to 40 g (330 mmol) oftris-(hydroxymethyl)-methylamine, dissolved in a mixture ofethanol/water/acetonitrile (200/50/200 ml) and stirred for 2 days at 45°C. It is evaporated to dryness and the residue is chromatographed onsilica gel (mobile solvent: methylene chloride/ethanol 15:1).

Yield: 97 g (57% of theory) of a vitreous solid

Elementary analysis:

Cld: C 51.24 H 6.45 N 8.15

Fnd: C 51.41 H 6.55 N 8.02

b)1-((α,α,α-Tris(hydroxymethyl)-methyl)-4,7,10-tris(p-tolylsulfonyl)-1,4,7,10-tetraazacyclododecane

95 g (184.2 mmol) of the title compound of Example 11a) is dissolved in900 ml of dimethylformamide and 24.31 g (1013 mmol) of sodium hydride isadded. It is stirred for 2 hours at room temperature, then it is heatedto 100° C. 104.6 g (184.2 mmol) of N-bis2-(4-methylphenylsulfonyloxy)-ethyl!-4-methyl-phenylsulfonamide,dissolved in 700 ml of dimethylformamide, is instilled in this solutionover 3 hours and then stirred overnight at 100° C. It is evaporated todryness in a vacuum, the residue is taken up in 2000 ml of water andextracted 5 times with 300 ml of methylene chloride each. The organicphase is dried on magnesium sulfate and evaporated to dryness. Theresidue is chromatographed on silica gel (mobile solvent =methylenechloride/ethanol 20:1).

Yield: 50.36 g (37% of theory) of a cream-colored solid

Elementary analysis:

Cld: C 53.64 H 6.27 N 7.58 S 13.02

Fnd: C 53.75 H 6.38 N 7.49 S 12.87

c)1-(α,α,α-Tris(methoxymethyl)-methyl)-4,7,10-tris(p-tolylsulfonyl)-1,4,7,10-tetraazacyclododecane

50 g (67.66 mmol) of the title compound of Example 11b) is dissolved in500 ml of dimethylformamide and 6.5 g (270.64 mmol) of sodium hydride isadded. It is stirred for 6 hours at room temperature. Then, 38.4 g(270.64 mol) of iodomethane, dissolved in 100 ml of dimethylformamide,is instilled over 30 minutes and then stirred overnight at 50° C. 2000ml of ice water is carefully added and extracted 3 times with 300 ml ofethyl acetate. The organic phase is shaken out twice with 10% commonsalt solution and then dried on magnesium sulfate. After concentrationby evaporation of the organic phase in a vacuum, the residue ischromatographed on silica gel (mobile solvent =methylenechloride/acetone 15:1).

Yield: 47.56 g (90% of theory) of a colorless solid

Elementary analysis:

Cld: C 55.36 H 6.71 N 7.17 S 18.44

Fnd: C 55.43 H 6.80 N 7.05 S 18.30

d) 1-(α,α,α-Tris(methoxymethyl)-methyl)-1,4,7,10-tetraazacyclododecane

39.75 g (1.73 mol) of sodium is added in portions to 45 g (57.62 mmol)of the title compound of Example 11c) in 1000 ml of n-butanol at 100° C.and it is stirred overnight at this temperature. It is cooled to roomtemperature, and 1000 ml of 20% common salt solution is added. Theorganic phase is separated and evaporated to dryness in a vacuum. Theresidue is chromatographed on silica gel (mobile solvent=ethanol/25%ammonia-water solution 10:1).

Yield: 12.29 g (67% of theory) of a pale yellow oil, which solidifieswith standing

Water content: 5.1%

Elementary analysis (relative to anhydrous substance):

Cld: C 56.57 H 10.76 N 17.59

Fnd: C 56.40 H 10.85 N 17.43

e)1-(α,α,α-Tris(methoxymethyl)-methyl)-4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

12 g (37.68 mmol) of the title compound of Example 11d) is dissolved in200 ml of water and 26.2 g (188.4 mmol) of bromoacetic acid is added.The pH is brought to 9.5 with 6 N potassium hydroxide solution. It isheated to 60° C. and the pH is kept between 9.5-10 by adding 6 Npotassium hydroxide solution. After 24 hours of stirring at 60° C., itis cooled in an ice bath, adjusted with concentrated hydrochloric acidto pH 1 and evaporated to dryness. The residue is put on acation-exchange column (IR 120/H⁺ form). After flushing with water, theligand is eluted with 0.5 N aqueous ammonia solution. The fractions areconcentrated by evaporation and put on an anion-exchange column (IRA67/OH⁻ form). It is washed with water and then eluted with 0.5 N formicacid. It is evaporated to dryness in a vacuum, the residue is dissolvedin a little hot methanol and acetone is added. After cooling in an icebath, the title compound crystallizes out.

Yield: 13.17 g (71% of theory) of a vitreous solid

Water content: 9.3%

Elementary analysis (relative to anhydrous substance):

Cld: C 51.21 H 8.18 N 11.37

Fnd: C 51.13 H 8.31 N 11.24

f) Praseodymium complex of1-(α,α,α-tris(methoxymethyl)-methyl)-4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

4 g (8.12 mol) of the title compound of Example 11e) is dissolved in 40ml of water and 1.34 g (4.06 mol) of praseodymium oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with5 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 5 ml of weakly basicexchanger (IRA 67/OH⁻ form) at room temperature. Exchanger is filteredout, and it is freeze-dried.

Yield: 5.07 g (99% of theory) of a vitreous solid

Water content: 10.1%

Elementary analysis (relative to anhydrous substance):

Cld: C 40.01 H 5.92 N 8.89 Pr 22.35

Fnd: C 39.87 H 6.03 N 8.73 Pr 22.21

g) Europium complex of 1-(α,α,α-tris(methoxymethyl)-methyl)-4,7,10-tris(carboxymethyl) -1,4,7,10-tetraazacyclododecane

4 g (8.12 mmol) of the title compound of Example 11e) is dissolved in 40ml of water and 1.43 g (4.06 mol) of europium oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with5 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 5 ml of weakly basicexchanger (IRA 67/OH⁻ form) at room temperature. Exchanger is filteredout, and it is freeze-dried.

Yield: 5.10 g (98% of theory) of a vitreous solid

Water content: 9.7%

Elementary analysis (relative to anhydrous substance):

Cld: C 39.32 H 5.81 N 8.73 Eu 23.69

Fnd: C 39.25 H 5.96 N 8.61 Eu 23.55

h) Dysprosium complex of1-(α,α,α-tris(methoxymethyl)-methyl)-4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane

4 g (8.12 mmol) of the title compound of Example 11e) is dissolved in 40ml of water and 1.43 g (4.06 mol) of dysprosium oxide is added. It isstirred for 3 hours at 90° C. The solution is stirred for one hour with5 ml of acidic ion exchanger (AMB 252c/H⁺ form) and 5 ml of weakly basicexchanger (IRA 67/OH⁻ form) at room temperature. Exchanger is filteredout, and it is freeze-dried.

Yield: 5.24 g (99% of theory) of a vitreous solid

Water content: 8.9%

Elementary analysis (relative to anhydrous substance):

Cld: C 38.68 H 5.72 N 8.59 Dy 24.92

Fnd: C 38.51 H 5.83 N 8.47 Dy 24.81

EXAMPLE 12

a)10-(3,6-Dioxa-heptyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

3 g (8.66 mmol) of 1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane is stirred in 50 ml of dimethylformamide for 10hours with 1.83 g (10 mmol) of 1-bromo-3,6-dioxa-heptane, 100 mg ofsodium iodide and 4 g of potassium carbonate at 90° C. It isconcentrated by evaporation in a vacuum and the residue is spreadbetween 100 ml of water and 50 ml of diethyl ether. The aqueous phase isadjusted to pH 2 with 5 N hydrochloric acid and evaporated to dryness.The residue is refluxed with 200 ml of methanol, the undissolvedmaterial is filtered out, evaporated to dryness in a vacuum, the residueis dissolved in 50 ml of water, adjusted to pH 2 with 5 N hydrochloricacid and the solution is put on a column with 200 ml of cation exchangerIRC 50. It is eluted first with 0.5 l of water, which is discarded.Then, it is eluted with 0.5 l of 0.5 N ammonia solution. It isevaporated almost to dryness in a vacuum, mixed with 100 ml of water andenough cation exchanger IRC 50 is added with stirring to reach pH 3.5.The solution is then filtered and freeze-dried. 2.95 g of the titlecompound with a water content of 3.5% is obtained.

Elementary analysis (relative to anhydrous substance):

Cld: C 50.88 H 8.09 N 12.49

Fnd: C 50.92 H 7.81 N 12.32

b) Praseodymium complex of10-(3,6-dioxa-heptyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

2.50 g (5.57 mmol, relative to anhydrous substance) of the titlecompound of Example 12a) is stirred in 30 ml of water with 919 mg ofpraseodymium oxide for 4 hours at 85° C. It is cooled to roomtemperature, filtered, and the solution is stirred for one hour with 1.5ml of acidic ion exchanger (AMB 252c, H⁺ form) and 1.5 ml of basic ionexchanger (IRA 67, OH⁻ form). It is filtered, freeze-dried and 2.85 g ofthe light green title compound with a water content of 5.05% isobtained.

Elementary analysis (relative to anhydrous substance):

Cld: C 38.92 H 5.67 N 9.55 Pr 24.03

Fnd: C 38.69 H 5.91 N 9.71 Pr 23.89

c) Dysprosium complex of10-(3,6-Dioxa-heptyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Analogously to Example 12b), dysprosium oxide instead of praseodymiumoxide is used. 3 g of the title compound with a water content of 4.5% isobtained.

Elementary analysis (relative to anhydrous substance):

Cld: C 37.53 H 5.47 Dy 26.73 N 9.22

Fnd: C 37.71 H 5.70 Dy 26.59 N 9.38

EXAMPLE 13

Purpose of the Study:

In vivo temperature measurement on the anesthetized animal after i.v.administration of the compound produced according to Example 6c) with ¹H magnetic resonance spectroscopy (MRS). Comparison of the measurementresults with the measured values of a comparison measurement with atemperature sensor.

Procedure:

Hardware: Electric temperature sensor OTD 85, Ellab Company Nuclear spintomograph: SIS 85/310, SISCO Company, 2 Tesla magnet, Oxford Company.

For the ¹ H-MRS, a surface coil with .o slashed. 20 mm was placed in theliver area of the animal. Spectra with 3 X water suppression andexcitation with frequency-selective gaussian pulse (4 ms) with nt=1000and TR=0.25 sec were recorded.

Animal: Wistar Han rat, 150 g, n=3.

Substance: Compound produced according to Example 6c), aqueous solution,500 mmol/L, pH 7.4.

Dose: 0.75 to 1 mmol/kg i.v. The animals were anesthetized(Rompun-Ketavet) at the beginning of the study. Then, their bodytemperatures dropped considerably. In the nuclear spin tomographs, theanimals were placed on a water bed, which was initially left at roomtemperature. There was a waiting period until a constant temperature wasestablished, which was measured rectally with a temperature sensor.Then, the first dose of compound 6c) was administered and 6 spectra at4.3 minutes apiece were recorded in succession. Then, the rectaltemperature was measured again, then the water bed was heated to 41° C.,and again there was a waiting period until a constant rectal temperaturewas established in the animal. The rectal temperature increased duringthis heating by about 2°-3° C. After administration of a second dose ofcompound 6c) (the first dose had already been eliminated renally), 6spectra at 4.3 minutes apiece were recorded again. Then, the rectaltemperature was measured again.

The evaluation of the spectra was done by determination of the chemicalshift of the measurement signal from the water signal, which was used asreference. The conversion of the chemical shift of the measurementsignal to temperature was done by means of a calibration curve, whichwas recorded in bovine plasma at a concentration of 2.5 mmol/L ofcompound 6c) and which reflects as precisely as possibly the in vivoconditions.

Result:

In the table, the results of the measurement of the body temperatures ofthe three animals studied are summarized. The first column indicatesmean value ±1 standard deviation of the measurement with the temperaturesensor before and after spectroscopy. The measured values of 6 spectrawere averaged, and the difference between them and the results from thethermosensor is indicated in the second column. The standard deviationof the 6 ¹ H-MRS measured values are indicated in the third column andare used as a yardstick for the reproducibility of the measuringprocess.

    ______________________________________                                                        Measuring dif-                                                                ference                                                                       between                                                              Temperature                                                                            .sup.1 H-MRS and the                                                                       Reproducibil-                                           sensor, rectal                                                                         temperature  ity of .sup.1 H-MRS                                     (n = 2)  °C.!                                                                   sensor  °C.!                                                                        (n = 6)  °C.!                             ______________________________________                                        animal,                                                                       anesthesia                                                                    1        31.5 ± 0.0                                                                            +2.3         ±0.4                                      2        29.9 ± 0.7                                                                            +0.5         ±0.6                                      3        30.3 ± 0.4                                                                            -1.1         ±0.3                                      animal,                                                                       anesthesia +                                                                  heated                                                                        1        34.5 ± 0.1                                                                            0            ±0.2                                      2        31.6 ± 0.7                                                                            +1.4         ±0.4                                      3        33.3 ± 0.6                                                                            -0.6         ±0.3                                      ______________________________________                                    

In the case of the anesthetized animals, with one exception, a goodcorrespondence (deviation<1.5° C.) between the measured values of thetemperature sensor and ¹ H-MRS was found. In this case, it can be takeninto consideration that the temperatures that are measured by the twomethods do not necessarily have to correspond exactly since they aremeasured in different areas of the body (temperature sensor rectally andspectroscopy in the liver area). The reproducibility of the 6 spectrarespectively in one animal was good (about ±0.5° C.). The dose of 0.75to 1 mmol/kg is sufficient with a measurement by the surface coil (about5 ml of detected measured volume) to record several spectra withinformative values over a period of about 30-45 minutes p.a.

Conclusion:

With compound 6c), a temperature difference of 1°-2° C. can be depictedin a limited volume with sufficient reliability (±0.5° C.). Themeasuring period for an individual spectrum is about 5 minutes.

Bibliography:

(1) R. Duerst et al., Rev. Sci. Instrum. 36 (1965) 1896, F. Conti, Rev.Sci. Instrum. 38 (1967) 128, A. L. Van Geet, Anal. Chem. 40 (1968) 2227,A. L. Van Geet, Anal. Chem. 42 (1970) 678, C. Ammann et al., J. Magn.Reson. 46 (1982) 319;

(2) D. R. Vidrin et al., Anal. Chem. 48 (1976) 1301;

(3) R. K. Gupta et al., J. Magn. Reson. 40 (1980)587;

(4) J. T. Bailey et al., J. Magn. Reson. 37 (1980) 353;

(5) P. E. Peterson, Anal. Chem. 50 (1978) 298;

(6) B. A. Berkowitz et al., NMR in Biomedicine 5 (1992) 65;

(7) M. J. Foster et al., J. Magn. Reson. 65 (1985) 497;

(8) K. Roth, Magn. Reson. Chem. 25 (1987) 429

(9) EP 0 095 124.

We claim:
 1. A method for determining temperature which comprises determining the change in chemical shift of a complex subject to NMR spectroscopy, wherein the complex is a macrocyclic metal complex of at least one metal ion of an element of atomic numbers 21-29, 42, 44 or 57-70 and a complexing agent of formula I ##STR5## in which n means the numbers 0 or 1,R¹ independently of one another, stand for a hydrogen atom or a metal ion equivalent, R³ stands for a hydrogen atom, a straight-chain or branched C₁ -C₁₀ alkyl group, which is optionally substituted by 1-5 C₁ -C₆ alkoxy groups, hydroxy-C₁ -C₆ alkyl groups and/or hydroxy groups, R² means a straight-chain or branched C₁ -C₁₀ alkylene group, which optionally is interrupted by 1 to 5 oxygen atoms and/or carbonyl groups and/or optionally is substituted by 1 to 5 hydroxy groups, C₁ -C₆ alkoxy-C₁ -C₆ alkyl groups, --OR⁴, --CO--NR⁵ R⁶, --NR⁵ R⁶ and/or --NR⁵ --CO--R⁶ radicals, in which R⁴ stands for a straight-chain or branched C₁ -C₄ alkyl radical and R⁵, R⁶, independently of one another, have the meaning of R³, and A stands for a hydrogen atom or a second macrocyclic radical of general formula II, ##STR6## in which n, R¹ and R³ have the indicated meanings, where free carboxylic acid groups that are not required for complexing a metal ion are present optionally as a salt of an inorganic or organic base or amino acid and/or as an ester or amide and where at least two radicals R¹ stand for a metal ion equivalent.
 2. The method of claim 1, wherein the macrocyclic metal complex contains, as radical R² --A, a --CH₂ CH₂ OCH₃, --CH₂ CH₂ O--C(CH₃)₃, --CH₂ --CH(OH)--CH₂ OCH₃, --CH₂ CH(OH)--CH₂ O--CH(CH₃)₂, --CH₂ --CH(OH)--CH₂ O--C(CH₃)₃, --CH₂ --CH(OH)--CH₃, --CH(CH₂ OCH₃)₂, --CH(CH₂ OCH₃)--CH(OH)CH₂ OH, --CH₂ --CH₂ --NH--CH₃, --CH₂ --CH₂ --N(CH₃)₂, --CH₂ --CO--N(CH₃)₂, --CH₂ --CH₂ --O--CH₂ --Ch₂ --O--Ch₃, or --C(CH₂ OCH₃)₃ group.
 3. The method of claim 1, wherein the macrocyclic metal complex is a praseodymium complex of 10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane.
 4. The method of claim 1, wherein the macrocyclic metal complex is a europium complex of 10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclo-dodecane
 5. The method of claim 1, wherein the change of chemical shift of at least two different macrocyclic metal complexes is determined, wherein the chemical shift of one complex exhibits a negative temperature gradient and the chemical shift of another complex exhibits a positive temperature gradient.
 6. The method of claim 1, wherein the radical R² --A is --CH₂ CH₂ OCH₃ or --CH₂ CH₂ OC(CH₃)₃.
 7. The method of claim 1, wherein the change in chemical shift is independent of ionic strength, pH or oxygen partial pressure.
 8. The method of claim 1, wherein at least one metal ion is a paramagnetic metal ion.
 9. The method of claim 1, wherein at least one metal ion is a lanthanoid element ion.
 10. The method of claim 1, wherein the complex is administered to a patient and the temperature is determined in vivo.
 11. The method of claim 10, wherein the complex is administered in a dose of 0.005-20 mmol/kg body weight.
 12. The method of claim 10, wherein the temperature in a body tissue is determined.
 13. The method of claim 1, wherein the temperature is determined within an error range of ±0.5° C.
 14. The method of claim 1, wherein the measuring period for a single spectrum is about 5 minutes or less.
 15. A method for determining temperature in a body tissue in vivo which comprises measuring the change in chemical shift by NMR spectroscopy of a complex in or on the tissue wherein the complex is at least one metal ion of an element of atomic numbers 21-29, 42, 44 or 57-70 and a complexing agent of formula I ##STR7## in which n means the numbers 0 or 1,R¹ independently of one another, stand for a hydrogen atom or a metal ion equivalent, R³ stands for a hydrogen atom, a straight-chain or branched C₁ -C₁₀ alkyl group, which is optionally substituted by 1-5 C₁ -C₆ alkoxy groups, hydroxy-C₁ -C₆ alkyl groups and/or hydroxy groups, R² means a straight-chain or branched C₁ -C₁₀ alkylene group, which optionally is interrupted by 1 to 5 oxygen atoms and/or carbonyl groups and/or optionally is substituted by 1 to 5 hydroxy groups, C₁ -C₆ alkoxy-C₁ -C₆ alkyl groups, --OR⁴, --CO--NR⁵ R⁶, --NR⁵ R⁶ and/or --NR⁵ --CO--R⁶ radicals, in which R⁴ stands for a straight-chain or branched C₁ -C₄ alkyl radical and R⁵, R⁶, independently of one another, have the meaning of R³, and A stands for a hydrogen atom or a second macrocyclic radical of general formula II, ##STR8## in which n, R¹ and R³ have the indicated meanings, where free carboxylic acid groups that are not required for complexing a metal ion are present optionally as a salt of an inorganic or organic base or amino acid and/or as an ester or amide and where at least two radicals R¹ stand for a metal ion equivalent.
 16. The method of claim 15, further comprising administering the complex in a dose of 0.005-20 mmol/kg body weight.
 17. The method of claim 15, wherein the macrocyclic metal complex contains, as radical R² --A, a --CH₂ CH₂ OCH₃, --CH₂ CH₂ O--C(CH₃)₃, --CH₂ --CH(OH)--CH₂ OCH₃, --CH₂ CH(OH)--CH₂ O--CH(CH₃)₂, --CH₂ --CH(OH)--CH₂ O--C(CH₃)₃, --CH₂ --CH(OH)--CH₃, --CH(CH₂ OCH₃)₂, --CH(CH₂ OCH₃)--CH(OH)CH₂ OH, --CH₂ --CH₂ --NH--CH₃, --CH₂ --CH₂ --N(CH₃)₂, --CH₂ --CO--N(CH₃)₂, --CH₂ --CH₂ --O--CH₂ --Ch₂ --O--Ch₃, or --C(CH₂ OCH₃)₃ group.
 18. The method of claim 15, wherein the macrocyclic metal complex is a praseodymium complex of 10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane.
 19. The method of claim 15, wherein the macrocyclic metal complex is a europium complex of 10-(3-oxabutyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane.
 20. The method of claim 15, wherein the change of chemical shift of at least two different macrocyclic metal complexes is determined, wherein the chemical shift of one complex exhibits a negative temperature gradient and the chemical shift of another complex exhibits a positive temperature gradient.
 21. The method of claim 15, wherein the radical R² --A is --CH₂ CH₂ OCH₃ or --CH₂ CH₂ OC(CH₃)₃.
 22. The method of claim 15, wherein the change in chemical shift is independent of ionic strength, pH or oxygen partial pressure.
 23. The method of claim 15, wherein at least one metal ion is a paramagnetic metal ion.
 24. The method of claim 15, wherein at least one metal ion is a lanthanoid element ion.
 25. The method of claim 15, wherein the temperature in a body tissue is determined.
 26. The method of claim 15, wherein the temperature is determined within an error range of ±0.5° C.
 27. The method of claim 15, wherein the measuring period for a single spectrum is about 5 minutes or less. 